Novel coil-tubing ram blowout preventer

ABSTRACT

A coil-tubing ram blowout preventer is disclosed that includes a ram block and ram-block cavity each having a D-shaped cross section. The flat portion of the ram block&#39;s “D” corresponds to the flat portion of the cavity&#39;s “D” to prevent rotation of the ram block within the ram-block cavity. The ram block may be configured with selectively replaceable seals, slips, or shear blades to allow easy configuration of the ram block for various sizes of tubing. The shear blades may include a sealing component on one surface of the blade such that paired shear-ram-blocks may create two distinct sealing points when each sealing component engages the other blade when the shear rams are closed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/939,584, filed on Nov. 23, 2019, which application is incorporated herein by reference.

BACKGROUND

This invention pertains generally to a ram blowout preventer (BOP) for use in oil-and-gas-well operations. More specifically, the invention may be embodied in a ram BOP for use with coil-tubing operations.

Blowout preventers are well known in the art. They are used to prevent the flow of fluids from a well during various operations (e.g., drilling, completions, interventions). Typically, a BOP is configured as several valves (preventers) assembled in a stack and directly or indirectly connected to the wellhead. A BOP includes a wellbore passage through which equipment may be placed into the well and a sealing mechanism for closing the wellbore passage. Annular preventers include an annular packing element configured to close around equipment such as drill pipe, tubing, or wireline. Ram preventers (rams) include a pair of substantially linear plungers (ram blocks) disposed in cavities and configured with sealing (or other) elements such that the ram preventer is closed by extending the blocks radially in toward the center of the preventer passage. The sealing elements engage each other or equipment such as a drill pipe, tubing, or wireline. The present invention is directed to ram preventers.

A ram preventer for tubing application may include blind rams, shear rams, slip rams, or pipe rams. Blind rams are configured to seal the well through engagement of the two ram blocks when there is no equipment in the wellbore passage of the preventer. Shear rams are configured to shear through any equipment in the wellbore passage of the preventer. Slip rams (slips) are configured to engage the equipment and hold it in place (e.g., to keep it from slipping into the well). Pipe rams are configured to engage the outside of the equipment to create a seal.

Ram blocks may be configured for multiple purposes. For example, the blocks of a single ram preventer may be configured both for blind sealing and shearing. Similarly, blocks may be configured both to hold the equipment and seal around the equipment. Typically, multipurpose ram blocks require a larger vertical dimension than do single-purpose ram blocks. (“Vertical” here refers to the direction parallel to the BOP wellbore passage.)

Ram blocks are typically disposed in cavities that are oriented perpendicular to the BOP equipment passage. The ram blocks are typically attached to shafts extending from pistons that are used to position the ram block via application of hydraulic pressure (via an actuator).

In coil-tubing operations, the ram blocks and shafts are typically exposed to torqueing and twisting forces when closing. This is because tubing in the passage of the ram preventer is typically not centered in the passage (it is eccentered). When the ram preventer is closed and the ram blocks move linearly inward to engage the eccentered tubing in the passage, the ram blocks center the tubing in the passage. This centering tends to torque or twist the ram block in the ram cavity which, if allowed, would impair the sealing, shearing, or holding function of the BOP. It is common to use guide rods or keys to maintain proper alignment of the ram blocks during this centering process. The guide rods and keys add to design complexity and may be a source of failure.

In coil-tubing operations, blind/shear rams may be exposed to sharp and jagged tubing sections or shards created when the tubing is sheared. Thus, seals on these rams may be cut or nicked which can cause the seal to fail.

The seals and slips of coil-tubing ram blocks are designed for specific tubing diameters. Shear blades may also have different designs for different tubing diameters. Different tubing diameters typically require different seals and slips, and perhaps shear blades. It is expensive and cumbersome to require different BOPs or replacement of ram blocks within a BOP for operations with different tubing sizes.

Accordingly, there is a need for a ram preventer of reduced size and complexity to improve the safety and efficiency of coil-tubing operations.

SUMMARY

In one aspect of the invention, a ram preventer includes a ram block having a cross-sectional shape roughly in the shape of a “D” (i.e., a cross section that is substantially circular but for a single flat portion having a length less than one-half of the perimeter of the cross section). The body of the ram preventer includes a ram-block cavity shaped complementary to the cross-sectional shape of the ram block (i.e., the cavity is defined by a cylindrical surface having a cross section that is substantially circular but for a single flat portion having a length less than one-half of the perimeter of the cross section). When the ram block is placed in the ram-block cavity, the flat portion of the block corresponds to the flat portion of the cavity to prevent rotation of the block within the cavity.

In another aspect of the invention, the ram block may be configured with a replaceable seal, slip, or blade insert (or combination insert). This enables efficient configuration of the ram block for a variety of tubing sizes without the need to have and maintain size-specific blocks. The body of the ram block may thus be used in a variety of applications simply by using the appropriate insert.

In another aspect of the invention, the BOP may include blind/shear rams comprising a pair of D-shaped ram blocks each with a shear blade that includes an elastomeric component on one surface of the blade. The ram blocks are configured to engage each other such that when the rams are closed the elastomer of one blade engages the surface of the other, and vice versa. This forms two distinct sealing points and thereby provides a redundant blind/shear seal to lower the risk of BOP seal failure due to a sealing component that was nicked or cut by the sheared tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings where:

FIG. 1 is a perspective cutaway view illustrating an exemplary two-ram BOP according to an aspect of the invention.

FIGS. 2A-2C are various views of an exemplary two-ram BOP according to an aspect of the invention.

FIG. 3 is a perspective view of a four-ram BOP according to an aspect of the invention.

FIGS. 4A-4E are various views of a single-ram BOP according to an aspect of the invention.

FIGS. 5A-5B are various views of a D-shaped ram block according to an aspect of the invention.

FIGS. 6A-6B are various views of another D-shaped ram block according to an aspect of the invention.

FIGS. 7A-7C are various views of another D-shaped ram block according to an aspect of the invention.

FIG. 8 depicts a closed shear ram preventer, illustrating a redundant seal, according to an aspect of the invention.

DETAILED DESCRIPTION

In the summary above, and in the description below, reference is made to particular features of the invention in the context of exemplary embodiments of the invention. The features are described in the context of the exemplary embodiments to facilitate understanding. But the invention is not limited to the exemplary embodiments. And the features are not limited to the embodiments by which they are described. The invention provides a number of inventive features which can be combined in many ways, and the invention can be embodied in a wide variety of contexts. Unless expressly set forth as an essential feature of the invention, a feature of a particular embodiment should not be read into the claims unless expressly recited in a claim.

Except as explicitly defined otherwise, the words and phrases used herein, including terms used in the claims, carry the same meaning they carry to one of ordinary skill in the art as ordinarily used in the art.

Because one of ordinary skill in the art may best understand the structure of the invention by the function of various structural features of the invention, certain structural features may be explained or claimed with reference to the function of a feature. Unless used in the context of describing or claiming a particular inventive function (e.g., a process), reference to the function of a structural feature refers to the capability of the structural feature, not to an instance of use of the invention.

Except for claims that include language introducing a function with “means for” or “step for,” the claims are not recited in so-called means-plus-function or step-plus-function format governed by 35 U.S.C. § 112(f). Claims that include the “means for [function]” language but also recite the structure for performing the function are not means-plus-function claims governed by § 112(f). Claims that include the “step for [function]” language but also recite an act for performing the function are not step-plus-function claims governed by § 112(f).

Except as otherwise stated herein or as is otherwise clear from context, the inventive methods comprising or consisting of more than one step may be carried out without concern for the order of the steps.

The terms “comprising,” “comprises,” “including,” “includes,” “having,” “haves,” and their grammatical equivalents are used herein to mean that other components or steps are optionally present. For example, an article comprising A, B, and C includes an article having only A, B, and C as well as articles having A, B, C, and other components. And a method comprising the steps A, B, and C includes methods having only the steps A, B, and C as well as methods having the steps A, B, C, and other steps.

Terms of degree, such as “substantially,” “about,” and “roughly” are used herein to denote features that satisfy their technological purpose equivalently to a feature that is “exact.” For example, a component A is “substantially” perpendicular to a second component B if A and B are at an angle such as to equivalently satisfy the technological purpose of A being perpendicular to B.

Except as otherwise stated herein, or as is otherwise clear from context, the term “or” is used herein in its inclusive sense. For example, “A or B” means “A or B, or both A and B.”

FIG. 1 is a partially-exploded cutaway perspective view depicting an exemplary two-ram BOP 100 according to an aspect of the invention. The BOP 100 utilizes four D-shaped ram blocks 102 and corresponding D-shaped ram cavities 104. Each ram block 102 is positioned in its corresponding ram cavity 104 through a hydraulic ram actuator 106. The top-left actuator 106 is depicted as disconnected from the preventer body 108 to reveal the top-left ram block 102 and top-left ram cavity 104.

The ram block 102 and ram cavity 104 are D-shaped in that the ram block 102 has a form roughly of a circle truncated to form a flat portion on one side such that the front profile of the ram block 102 is similar in shape to the letter “D” and the ram cavity 104 is shaped to receive the ram block 102. (Exemplary D-shaped profiles of exemplary ram blocks are depicted in FIGS. 5B, 6B, and 7B. An exemplary D-shaped profile of an exemplary ram cavity is depicted in FIG. 4E.) When the ram block 102 is within the ram cavity 104, the flat portions of the block 102 and cavity 104 engage to limit rotation of the block 102 within the cavity 104. Because of the D-shape of the ram block 102 and ram cavity 104, it is not necessary to include hardware to prevent rotation of the block 102 within the cavity 104 as would be required, for example, with blocks and cavities of substantially circular profiles. For example, the D-shape of the block 102 and cavity 104 limits rotation of the block 102 without the use of conventional anti-rotation mechanisms such as guide rods and keyed rams. Other features of the exemplary BOP 100 may include an internal equalization valve 150 having a carbide ball seat, hydraulic fittings 152 of a wide variety of styles, ¾″ hydraulic ports 154 for fast actuator cycle times, integrated lift point 156, bumper 158 to protect the hydraulic fittings, and connection flange 160.

FIGS. 2A through 2C depict an exemplary two-ram BOP 200. This is similar to BOP 100 of FIG. 1. FIG. 2A is a front view, FIG. 2B is a rear view, and FIG. 2C is a partially-exploded cutaway perspective view. The BOP 200 includes four ram blocks 202 and cavities 204. The ram blocks 202 are positioned using four actuators 206 that are attached to the preventer body 208. The BOP 200 includes lifting points 210, hydraulic fittings 212, and equalization valves 214.

FIG. 3 depicts an exemplary four-ram BOP 300. This is similar to the two-ram BOPs of FIGS. 1 and 2A-2C with the primary difference being the number of rams and associated components. The four-ram BOP 300 has eight ram blocks and eight actuators.

FIGS. 4A through 4E depict an exemplary single-ram BOP 400. This is similar to the previously described multi-ram BOPs. FIG. 4A is a perspective view of the BOP 400. FIGS. 4B and 4C are front and back views, respectively. FIG. 4D is a partially-exploded cutaway back view revealing a ram shaft 416. FIG. 4E is a side view of the preventer body 408, showing the profile of the ram cavity 404. The ram cavity 404 includes a flat portion 404 a and a curved portion 404 b. As previously explained, the flat portion 404 a of the surface of the ram cavity 404 engages a corresponding flat portion of a ram block such as to resist rotation of the ram block within the cavity 404. This can be better understood with reference to FIGS. 5B, 6B, and 7B, which each depicts the corresponding profile of a different exemplary ram block.

FIGS. 5A and 5B depict an exemplary D-shaped ram block 500 configured as a pipe ram block. FIG. 5A is a perspective view, FIG. 5B is a front view. The ram block 500 includes: (1) a sealing component 506 (e.g., an elastomeric component) configured to engage and seal against tubing, (2) tubing guides 502, 504 configured to engage and position tubing for sealing against the sealing component 506, and (3) a cutout 508 configured as a fluid bypass channel to prevent backpressure affecting ram closure or opening. The ram block 500 also includes a curved surface 500 b and a flat surface 500 a which correspond to the curved and flat surfaces of the ram-block cavity. The sealing component 506 may be selected according to the tubing size and inserted into the body of the ram block 500 such that the ram block 500 is configurable for various tubing sizes instead of being dedicated to a particular tubing size.

FIGS. 6A and 6B depict an exemplary D-shaped ram block 600 configured as a combination pipe and slip ram block. FIG. 6A is a perspective view, FIG. 6B is a front view. The ram block 600 includes: (1) a sealing component 606 configured to engage and seal against tubing, (2) toothed or scored slip components 605, 607 configured to engage and hold tubing, (3) tubing guides 602, 604 configured to engage and position tubing for sealing against the sealing component 606, and (4) a cutout 608 configured as a pressure relief passage. The ram block 600 also includes a curved surface 600 b and a flat surface 600 a which correspond to the curved and flat surfaces of the ram-block cavity. The sealing component 606 and the slip components 605, 607 may be selected according to the tubing size and inserted into the body of the ram block 600 such that the ram block 600 is configurable for various tubing sizes instead of being dedicated to a particular tubing size. The slip components 605, 607 may be replaced with smooth components such that the ram block 600 may be configured as a pipe ram rather than a pipe/slip ram.

FIGS. 7A through 7C depict an exemplary D-shaped ram block 700 configured as a combination shear and blind ram block. FIGS. 7A and 7C are perspective views, FIG. 7B is a front view. The ram block 700 includes: (1) a shearing component (blade) 706 configured to engage and cut through tubing, (2) a sealing component 710 shown on the underside of the blade 706 that is configured to engage and seal against the shearing blade of the paired ram block in the preventer, and (3) a cutout 708 configured as a pressure relief passage. The ram block 700 also includes a curved surface 700 b and a flat surface 700 a which correspond to the curved and flat surfaces of the ram-block cavity. The blade 706 and sealing component 710 may be selected according to the tubing size and inserted into the body of the ram block 700 such that the ram block 700 is configurable for various tubing sizes instead of being dedicated to a particular tubing size.

FIG. 8 depicts paired blind/shear ram blocks 700, 700* of a ram preventer positioned to seal the BOP. The blades 706, 706* are inverted relative to each other but are otherwise identical. When closed, the sealing component 710* of the inverted blade 706* engages a surface 706 a of the noninverted blade 706 and the sealing component 710 of the noninverted blade 706 engages a surface 706 a* of the inverted blade 706*. Thus, there are two sealing points. This creates a redundancy which protects against failure: if one of the sealing components 710, 710* is cut or nicked, the preventer will seal so long as the other sealing component 710*, 710 remains intact.

While the foregoing description is directed to the preferred embodiments of the invention, other and further embodiments of the invention will be apparent to those skilled in the art and may be made without departing from the basic scope of the invention. And features described with reference to one embodiment may be combined with other embodiments, even if not explicitly stated above, without departing from the scope of the invention. The scope of the invention is defined by the claims which follow. 

The invention claimed is:
 1. A coil-tubing blowout preventer comprising: (a) a body having a first ram-block cavity defined by a cylindrical surface having a cross section that is substantially circular but for a single flat portion having a length less than one-half of the perimeter of the cross section; and (b) a first ram block having a cross section that is substantially circular but for a single flat portion having a length less than one-half of the perimeter of the cross section; (c) wherein the flat portion of the ram-block cavity corresponds to the flat portion of the ram block.
 2. The coil-tubing blowout preventer of claim 1 further comprising a second ram block wherein: (a) the first ram block includes a first shear blade having a first surface and a first elastomeric material bonded to the first shear blade; (b) the second ram block includes a second shear blade having a second surface and a second elastomeric material bonded to the second shear blade; (c) the first elastomeric material is configured to engage the second surface when the first and second ram blocks are in the closed position and thereby form a first seal between the first shear blade and the second shear blade; and (d) the second elastomeric material is configured to sealingly engage the first surface when the first and second ram blocks are in the closed position and thereby form a second seal between the first shear blade and the second shear blade.
 3. The coil-tubing blowout preventer of claim 1 wherein the first ram block includes a body and an elastomeric component that is configured to engage the outside surface of tubing to thereby form a seal between the body and the tubing and wherein the elastomeric component may be selectively removed from or inserted into the body.
 4. The coil-tubing blowout preventer of claim 1 wherein the first ram block includes a body and a toothed or scored component that is configured to engage the outside surface of tubing to thereby hold the tubing in place relative to the body and wherein the toothed or scored component may be selectively removed from or inserted into the body.
 5. The coil-tubing blowout preventer of claim 1 wherein the first ram block includes a body and shear blade that is configured to shear through tubing and wherein the shear blade may be selectively removed from or inserted into the body. 